Correspondence between discrete and piecewise linear models of gene regulatory networks

International audienceWe know that some proteins can regulate the expression of genes in a living organism. The regulation of gene expression occurs through networks of regulatory interactions in a non linear way between DNA, RNA, proteins and some molecules, called genetic regulatory networks. It is becoming clear that mathematical models and tools are required to analyze these complex systems. In the course of his study on gene regulatory networks R. Thomas proposed a discrete framework that mimics the qualitative evolution of such systems. Such discrete models are of great importance because kinetic parameters are often non measurable in vivo and available data are often of qualitative nature. Then Snoussi proved consistency between the discrete approach of R. Thomas and Piecewise Linear Differential Equation Systems, which are easy to construct from interaction graph and thresholds of interactions. Our work focuses on the relationships between both approaches: we will prove a result of correspondence between the two models. Finally, we will give some short description of a Maple program which can compute a discrete path, given the ordinary differential equation and starting box

Near-field BLEVE overpressure effects: The shock start model

International audienceThis paper presents the results of a small scale experimental study of BLEVE overpressure effects. Testing consisted of a sealed aluminum tube (0.6 L) filled with either water or propane, being heated by a flame until the internal pressure led to catastrophic failure and explosion. Three parameters were controlled during the experiments: the failing pressure, the weakened length on the tube and the fill level. BLEVEs were obtained with tests involving water and propane. Blast gages and optical techniques were used to characterize the shock wave escaping from the failing tube. The results obtained suggest that the lead shock was primarily generated by the vapor space. Overpressure results obtained were compared with the predictions of existing models and found to be in reasonable agreement except for overpressures measured vertically above the cylinder where the overpressures were highest. A prediction model based on only vapor space characteristics was developed. Images show that the shock was fully formed at some distance away from the vessel opening and this was due to the non-ideal opening of the vessel. The model developed was based on the characteristics of the shock when fully formed away from the tube. These characteristics were defined using a combination of imaging, pressure measurements, and predictions from shock tube theory

Applicabilité de la différentiation automatique à un système d'équations aux dérivées partielles régissant les phénomènes thermohydrauliques dans un tube chauffant

Dans ce rapport, nous étudions l'applicabilité de la différentiation automatique à un système d'équations aux dérivées partielles régissant les phénomènes thermohydrauliques dans un tube chauffant. En particulier, il s'agit de voir si le différentiateur Odyssée développé à l'INRIA dans le projet SAFIR peut différentier un code tel que Thyc-1D  (maquetteà une dimension en espace du code Thyc), lequel comporte 23 sous-routines de calcul. Resume AN |The applicability of automatic differentiation on a set of partial differential equations governing thermohydraulic phenomena in heat exchangers is examined. More specifically, the challenge is to differentiate the code Thyc-1D, a 1-D mockup of the 3-D code Thyc implementing these equations, with the automatic differentiator Odyssée with as few manual interventions as possible. The code to differentiate contains 23 routines, including linear solvers and black-box functions, whose code is not availabl

Caractérisation et modélisation des effets de surpression en champ proche et du chargement au sol du BLEVE

Boiling Liquid Exploding Vapor Explosion (BLEVE) is one of the most feared accident in the industry. Even though it has been studied for over 6 decades, many safety questions remain poorly answered: what happens if a BLEVE occurs in a congested urban or industrial area? What if a road tanker BLEVE happens on a bridge? These questions require to look closer to the vessel. This work focuses on understanding the physics involved in overpressure generation in the near field surrounding of the vessel, to understand the contribution of the fluid phases (liquid and vapor) in the near-field hazards of a BLEVE. For this purpose, a small scale experimental prototype was designed to reproduce realistic BLEVE failure. Twenty-four propane BLEVEs were performed. A wide range of data was recorded from these tests: blast overpressure all around the vessel, transient pressure inside the vessel, ground loading under the vessel, and high speed imaging through various angles. Results give more insight on the anisotropy of the pressure field around the cylindrical vessel. It also shows a strong dependency between vapor content and maximum overpressure from the lead shock. Moreover, the chronology of the phase change observed through transient pressure measurements show that the main contributor of the maximum overpressure is the vapor phase. The phase change is studied through pressure transient in the vessel and high speed imaging, giving a better understanding of the time scales involved with this phenomenon. Finally, ground loading measurements are analyzed to give insight on the order of magnitude involved in this hazard.Le BLEVE (Boiling Liquid Exploding Vapor Explosion) est l’un des accidents les plus craints dans l’industrie. Bien qu’il soit étudié depuis plus de soixante ans, certains dangers et situations restent mal anticipés, tels que : quelles seraient les conséquences de la surpression d’un BLEVE dans un milieu urbain confiné ? Qu’adviendrait-il si un camion de transport de GPL venait exploser sur un pont ? Ces questions nécessitent d’étudier la physique du BLEVE au plus proche du conteneur. Ce travail explore les phénomènes physiques générant la surpression aérienne en champ proche de l’explosion, en essayant de comprendre la contribution des phases du contenu (liquide et vapeur) dans les dangers en champ proche du BLEVE. Un prototype expérimental petite échelle a été conçu dans le but de reproduire les BLEVE de cuves cylindriques de manière réaliste. Vingt-quatre BLEVEs de propane ont été effectués. Un large spectre de données a été collecté lors de ces tests : surpression aérienne dans de multiples directions autour du conteneur, variations de pression dans le conteneur avant et après rupture, chargement au sol dû à l’explosion, visualisations en imagerie rapide selon un certain nombre d’angles. Les résultats montrent une dépendance forte entre les caractéristiques de la phase vapeur et la suppression maximale générée par l’explosion. La reconstruction chronologique du phénomène confirme ce résultat. Cependant, la phase liquide joue un rôle capital dans la génération du chargement au sol, qui est un danger considérable, mais peu considéré jusque-là

Characterization and modeling of near-field overpressures and ground loading effects of BLEVE

Le BLEVE (Boiling Liquid Exploding Vapor Explosion) est l’un des accidents les plus craints dans l’industrie. Bien qu’il soit étudié depuis plus de soixante ans, certains dangers et situations restent mal anticipés, tels que : quelles seraient les conséquences de la surpression d’un BLEVE dans un milieu urbain confiné ? Qu’adviendrait-il si un camion de transport de GPL venait exploser sur un pont ? Ces questions nécessitent d’étudier la physique du BLEVE au plus proche du conteneur. Ce travail explore les phénomènes physiques générant la surpression aérienne en champ proche de l’explosion, en essayant de comprendre la contribution des phases du contenu (liquide et vapeur) dans les dangers en champ proche du BLEVE. Un prototype expérimental petite échelle a été conçu dans le but de reproduire les BLEVE de cuves cylindriques de manière réaliste. Vingt-quatre BLEVEs de propane ont été effectués. Un large spectre de données a été collecté lors de ces tests : surpression aérienne dans de multiples directions autour du conteneur, variations de pression dans le conteneur avant et après rupture, chargement au sol dû à l’explosion, visualisations en imagerie rapide selon un certain nombre d’angles. Les résultats montrent une dépendance forte entre les caractéristiques de la phase vapeur et la suppression maximale générée par l’explosion. La reconstruction chronologique du phénomène confirme ce résultat. Cependant, la phase liquide joue un rôle capital dans la génération du chargement au sol, qui est un danger considérable, mais peu considéré jusque-là.Boiling Liquid Exploding Vapor Explosion (BLEVE) is one of the most feared accident in the industry. Even though it has been studied for over 6 decades, many safety questions remain poorly answered: what happens if a BLEVE occurs in a congested urban or industrial area? What if a road tanker BLEVE happens on a bridge? These questions require to look closer to the vessel. This work focuses on understanding the physics involved in overpressure generation in the near field surrounding of the vessel, to understand the contribution of the fluid phases (liquid and vapor) in the near-field hazards of a BLEVE. For this purpose, a small scale experimental prototype was designed to reproduce realistic BLEVE failure. Twenty-four propane BLEVEs were performed. A wide range of data was recorded from these tests: blast overpressure all around the vessel, transient pressure inside the vessel, ground loading under the vessel, and high speed imaging through various angles. Results give more insight on the anisotropy of the pressure field around the cylindrical vessel. It also shows a strong dependency between vapor content and maximum overpressure from the lead shock. Moreover, the chronology of the phase change observed through transient pressure measurements show that the main contributor of the maximum overpressure is the vapor phase. The phase change is studied through pressure transient in the vessel and high speed imaging, giving a better understanding of the time scales involved with this phenomenon. Finally, ground loading measurements are analyzed to give insight on the order of magnitude involved in this hazard

Searching for the unspeakable : An iterative approach to designing a corpus of texts about a taboo topic

Taboo topics tend, by their definition, to be censored in language use, and are thus often absent from discourse. When such topics are discussed, they tend to be referred to indirectly, for example through euphemistic language. This presents a challenge for the design and construction of topic-specific corpora, then, when the topic being investigated might be considered taboo within the culture and/or discourse context under study. In this article, we explore the challenges involved in attempting to construct a corpus of news media texts that are ‘about’ a taboo topic. Focusing on the case of incest – an issue deeply entrenched in social and linguistic taboos – we present an iterative, corpus-assisted approach to designing, assessing and (re)constructing a corpus of UK newspaper articles about this topic. As well as contributing to our understanding of the representation of incest in UK news media, this article underscores the importance of transparency and reflexivity in the process of (iterative) corpus design and serves to demonstrate how the reporting of this process might proceed in other studies whose data similarly represent a product of iterative design

Complication rare d'une paraostéoarthropathie de hanche (compression du tronc sciatique : à propos d'un cas)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF